Overshot assembly

ABSTRACT

An overshot assembly can include a distal body portion. The distal body portion can have a central axis, a length along the central axis, and an outer surface. An outer surface of the distal body portion can define, along at least a portion of the length, at least one drill string engagement portion having a first radial distance from the central axis of the distal body portion. The drill string engagement portion(s) can be configured to bias against and slide along an inner surface of a drill string. At least one recessed portion can be inwardly spaced from said first radial distance from the central axis. The recessed portion(s) can each be configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion. A plane that is perpendicular to the central axis of the distal body portion can extend through each drill string engagement portion of the at least one drill string engagement portion and each portion of the at least one recessed portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of the filing date of U.S. Provisional Patent Application No. 63/085,572, filed Sep. 30, 2020, and of U.S. Provisional Patent Application No. 63/235,951, filed Aug. 23, 2021. The entirety of each of these applications is hereby incorporated by reference herein.

FIELD

The disclosed invention relates to an overshot assembly for retrieving an inner tube head assembly.

BACKGROUND

During conventional drilling, after an inner tube of a head assembly is full of a sample (i.e., a core sample), an overshot assembly is lowered (or pumped) toward the bottom of a drill hole to retrieve the head assembly. Conventional overshot assemblies include heavy-duty lifting dogs that are configured to securely grab a spearhead (spearpoint) that is coupled to the proximal end of the head assembly. After engagement between the lifting dogs and the spearhead, the overshot is retrieved from the drill hole, and the sample is extracted from the inner tube. There is a need for an overshot that can be deployed and retrieved more quickly to increase the efficiency of the drilling process.

SUMMARY

Described herein, in one aspect, is an overshot assembly having a longitudinal axis can comprise a distal body portion defining a central bore. A proximal body portion can be coupled to the distal body portion. A spindle can be disposed within the central bore of the distal body portion. The spindle can be slidable relative to the distal body portion along the longitudinal axis. A latching assembly can be operatively coupled to the distal body portion and configured for movement about and between a retracted position and a deployed position. A sleeve can be rotatably coupled to the distal body portion about the longitudinal axis. At least one blocking element can be radially movable within the sleeve toward and away from the longitudinal axis. When the sleeve is in a first rotational position, the latching assembly can be retained in the deployed position and the at least one blocking element can be held radially outward of a radially-outermost surface of the sleeve. When the sleeve is in a second rotational position, the latching assembly can be movable between the retracted position and the deployed position, and the at least one blocking element can be not held radially outward of the radially-outermost surface of the sleeve.

In another aspect, an overshot assembly having a longitudinal axis can comprise a distal body portion defining a central bore. A proximal body portion can be coupled to the distal body portion. A sleeve that is rotatably coupled to the distal body portion about the longitudinal axis. At least one blocking element can be radially movable within the sleeve toward and away from the longitudinal axis. When the sleeve is in a first rotational position, the at least one blocking element is held radially outward of a radially-outermost surface of the sleeve. When the sleeve is in a second rotational position, the at least one blocking element is not held radially outward of the radially-outermost surface of the sleeve. When the sleeve is in the first rotational position, the at least one blocking element can extend sufficiently radially outward of the sleeve to inhibit insertion of the overshot assembly into a drill string.

In another aspect, an overshot assembly having a longitudinal axis can comprise a distal body portion defining a central bore. A proximal body portion can be coupled to the distal body portion. A sleeve can be rotatably coupled to the distal body portion about the longitudinal axis. When the sleeve is in a first rotational position, the latching assembly can be retained in the deployed position. When the sleeve is in a second rotational position, the latching assembly can be movable between the retracted position and the deployed position.

A method of using the overshot assemblies as disclosed herein can comprise inserting the distal end of the overshot assembly into a proximal end of a head assembly and rotating the sleeve until the sleeve is in the first rotational position.

An overshot assembly can include a distal body portion. The distal body portion can have a central axis, a length along the central axis, and an outer surface. An outer surface of the distal body portion can define, along at least a portion of the length, at least one drill string engagement portion having a first radial distance from the central axis of the distal body portion. The drill string engagement portion(s) can be configured to bias against and slide along an inner surface of a drill string. At least one recessed portion can be inwardly spaced from said radial distance from the central axis. The recessed portion(s) can each be configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion. A plane that is perpendicular to the central axis of the distal body portion can extend through each drill string engagement portion of the at least one drill string engagement portion and each portion of the at least one recessed portion.

Additional advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION OF THE DRAWINGS

These and other features of the preferred embodiments of the invention will become more apparent in the detailed description in which reference is made to the appended drawings wherein:

FIG. 1 is a side view of an overshot assembly in accordance with embodiments disclosed herein.

FIG. 2A is a cross section of a distal end of the overshot assembly, showing a latching assembly in an unlatched position. FIG. 2B is a cross section of the distal end of the overshot assembly, showing the latching assembly in a latched position.

FIG. 3A is a cross-sectional view of the overshot assembly in an unlocked configuration, taken in the plane shown in FIG. 1 . FIG. 3B is a cross-sectional view of the overshot assembly as in FIG. 1 in a locked configuration. FIG. 3C is a perspective view of a rotatable sleeve of the overshot assembly as in FIG. 1 . FIG. 3D is a cross-sectional view of the rotatable sleeve as in FIG. 3C.

FIG. 4 is a perspective view of a distal body portion of the overshot assembly as in FIG. 1 .

FIG. 5 is a cross-sectional view of an exemplary overshot assembly positioned within a drill string.

FIG. 6A is a side view of the overshot assembly of FIG. 1 before engaging a core tube assembly. FIG. 6B is a side view of the overshot assembly of FIG. 1 before after engaging core tube assembly.

FIG. 7 is an illustration of a step of rotating the sleeve to lock the overshot assembly to the core tube assembly.

FIG. 8 illustrates a perspective view of a step of using a locking pin to lock to retain the core tube to the overshot assembly.

FIG. 9 illustrates a perspective view of a step of attaching a release guard and removing the locking pin.

FIG. 10 illustrates a perspective view of a step in releasing the core tube by twisting the locking sleeve.

FIG. 11 illustrates a perspective view of a step of releasing the core tube by impacting the release guard against the drill string.

FIG. 12 illustrates a perspective view of a configuration for inserting the overshot assembly into the drill string.

FIG. 13 illustrates a perspective view showing a step of rotating the locking sleeve to lock the core tube to the overshot assembly.

FIG. 14 illustrates a perspective view showing a step of using a locking pin to lock to retain the core tube to the overshot assembly.

FIG. 15 is a view into a drill string of a distal end of an overshot assembly as disclosed herein.

FIG. 16 is a perspective view of a distal body portion of an overshot assembly omitting a twist sleeve.

FIG. 17 is a partial perspective view of an overshot assembly as disclosed herein, showing a swivel joint and a pivot joint.

FIG. 18 is a partial cross sectional view of the overshot assembly of FIG. 17 .

FIG. 19 is an exploded view of a portion of a head assembly having an adapter for use with the overshot assembly as disclosed herein.

FIG. 20 is an exploded view of a portion of an overshot assembly as disclosed herein having a plurality of removable segments.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. It is to be understood that this invention is not limited to the particular methodology and protocols described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

As used herein the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. For example, use of the term “a blocking element” can refer to one or more of such blocking elements, and so forth.

All technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs unless clearly indicated otherwise.

Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. Optionally, in some aspects, when values are approximated by use of the antecedent “about,” it is contemplated that values within up to 15%, up to 10%, up to 5%, or up to 1% (above or below) of the particularly stated value can be included within the scope of those aspects. Similarly, in some optional aspects, when values are approximated by use of the terms “approximately,” “substantially,” or “generally,” it is contemplated that values within up to 15%, up to 10%, up to 5%, or up to 1% (above or below) of the particular value can be included within the scope of those aspects. When used with respect to an identified property or circumstance, “substantially” or “generally” can refer to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property or circumstance, and the exact degree of deviation allowable may in some cases depend on the specific context.

As used herein, the term “proximal” refers to a direction toward a drill rig or drill operator (and away from a formation or borehole), while the term “distal” refers to a direction away from the drill rig or drill operator (and into a formation or borehole).

As used herein, the terms “optional” or “optionally” mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

As used herein, the term “at least one of” is intended to be synonymous with “one or more of” For example, “at least one of A, B and C” explicitly includes only A, only B, only C, and combinations of each.

The word “or” as used herein means any one member of a particular list and also includes any combination of members of that list.

It is to be understood that unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of aspects described in the specification.

The following description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatus, system, and associated methods of using the apparatus can be implemented and used without employing these specific details. Indeed, the apparatus, system, and associated methods can be placed into practice by modifying the illustrated apparatus, system, and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry.

U.S. Pat. No. 10,626,692, granted Apr. 21, 2020, to Drenth et al., which is hereby incorporated by reference herein in its entirety, discloses an overshot assembly that provides certain advantages over conventional overshot assemblies. The overshot assembly comprises a distal portion that is receivable into a proximal end of the head assembly. Optionally, the head assembly can comprise a spearpoint and an adapter that can couple at a first end to the spearhead and define the proximal end into which the overshot assembly is receivable. The distal portion of the overshot assembly comprises latch members that engage the head assembly to releasably couple the head assembly to the overshot assembly. The overshot assembly can optionally comprise a spindle and a distal body portion that is pivotable with respect to the spindle, wherein when the distal body portion is in a first rotational position with respect to the spindle, the latch members are locked in a deployed (latching) position and in a second rotational position, the latch members are movable about and between the deployed position and a retracted (release) position.

In some situations, the overshot assembly can be lowered to the bottom of the drill hole with the latch members inadvertently locked in the deployed (latching) position, preventing the overshot assembly from coupling to the head assembly, and requiring retrieval and re-lowering of the overshot assembly with the latch members. Further, the body of the overshot can cause significant drag through the drilling fluid in the drill string, thereby slowing the overshot's travel through the drill string. Accordingly, an overshot that can be deployed more quickly is desirable.

Disclosed herein, in various aspects and with reference to FIGS. 1-3B, is an overshot assembly 100 having a longitudinal axis 102. The overshot assembly 100 can comprise a distal body portion 104 and a proximal body portion 106 that is coupled to the distal body portion 104. Optionally, the distal body portion 104 can comprise a proximal component 104 a and a distal component 104 b that is coupled to (optionally, threadedly coupled to) the proximal component. The distal body portion 104 can define a central bore 108. A spindle 110 can be disposed within the central bore 108 of the distal body portion 104 and can be slidable relative to the distal body portion 104 along the longitudinal axis 102. A latching assembly 112 can be operatively coupled to the distal body portion 104 and configured for movement about and between a retracted position (FIG. 2A) and a deployed position (FIG. 2B).

In these aspects, proximal axial advancement of the distal body portion 104 relative to the spindle 110 can be configured to effect movement of the latching assembly 112 from its deployed position toward its retracted position. More particularly, as the distal body portion 104 move in a proximal direction relative to the spindle 110, the distal body portion 104 drives movement of the latching assembly 112 in a proximal direction until the latching assembly is positioned at an axial position where the spindle 110 is shaped to accommodate the latching assembly within the central bore of the distal body portion.

The latching assembly 112 can optionally comprise at least one latch member 114 (optionally, a plurality of latch members 114). It is contemplated that each latch member 114 of the at least one latch member can be at least one of a ball, a roller, a cylinder, a cam-shaped element, and the like. As one of skill in the art will appreciate, unlike conventional latching mechanisms for drilling applications in which axial movement of a spindle positioned within a body is tied to axial movement of the body (i.e., axial movement of the body results in a corresponding axial movement of the spindle), the disclosed overshot assembly permits independent axial movement of the spindle 110 and the distal body portion 104.

The distal body portion 104 can have a wall 32 that can define at least one distal radial opening 42 extending from an outer surface 36 of the wall 32 to the central bore 108 of the distal body portion. In these aspects, the at least one distal radial opening 42 can be configured to at least partially receive the at least one latch member 114 when the latching assembly 112 is in the deployed position. Thus, in use, when the distal body portion 104 is axially advanced in a proximal direction relative to the spindle 110, the surfaces of the distal body portion 104 that define the at least one distal radial opening 42 can contact the at least one latch member 114 and apply an axial force to the at least one latch member until the at least one latch member is positioned at an axial location in which it can be received within the central bore 108 of the distal body portion 104.

In one aspect, a distal portion 76 of the spindle 110 can have a wedge portion 82. In this aspect, the wedge portion 82 of the distal portion 76 of the spindle 110 can define a first driving surface 84. In operation, the latching assembly 112 can be positioned in engagement with the first driving surface 84 when the latching assembly 112 is in the deployed position (FIG. 2B), and upon axial advancement of the distal body portion 104 relative to the longitudinal axis 12, a proximal portion of the first driving surface 84 can define a recess that is configured to receive the latching assembly and permit radial movement of the latching assembly toward the retracted position (FIG. 2A). Optionally, it is contemplated that the wedge portion 82 can be tapered inwardly moving in a proximal direction such that the latching assembly 112 is gradually and progressively received within the central bore of the distal body portion as the distal body portion and the latching assembly are axially advanced in a proximal direction.

In additional aspects, when the at least one latch member 114 of the overshot is positioned in the retracted position, it is contemplated that the at least one latch member and the outer surface of the wall of the distal body portion 104 can define an outer diameter of the distal body portion of the overshot assembly 100 that is less than the inner diameter of the head assembly. In further aspects, and as further disclosed herein, it is contemplated that the at least one latch member 114 can be biased toward the deployed position. In exemplary aspects, the at least one latch member 114 can be spring-loaded toward the deployed position. In these aspects, it is contemplated that the spindle 110 can be spring-loaded toward an axial position in which the at least one latch member 114 is urged toward the deployed position (by wedge portion 82). Upon entry of the distal body portion 104 of the overshot 100 into the opening and central bore of the head assembly, it is contemplated that the inner surface of the retracting case and/or the proximal end of the head assembly can be configured to force the at least one latch member 114 into the retracted position (from the deployed position) to accommodate the distal body portion of the overshot within the head assembly. In further exemplary aspects, the at least one groove can be configured to securely receive the at least one latch member 114 of the overshot 100 when the at least one latch member is positioned in the deployed position. In still further exemplary aspects, it is contemplated that the proximal end of the head assembly can be configured to abut a portion of the overshot 100 when the at least one latch member 114 is received within the at least one groove of the retracting case.

Upon movement of the distal body portion in a proximal direction and parallel or substantially parallel to the longitudinal axis 102 (such that the first driving surface 84 of the wedge portion 82 is disengaged from the at least one latch member 114), the at least one latch member 114 can be retracted relative to the inner surface of the head assembly such that the at least one latch member disengages the inner surface of the head assembly.

It is contemplated that the latching members 114 can be sized to protrude beyond the wall 32 of the distal body portion 104 and securely engage the inner surface of the head assembly while maintaining secure engagement with the distal body portion of the overshot assembly 100. Thus, it is contemplated that, upon engagement between the latching members 114 and the inner surface of the head assembly, the latching members (and the head assembly) can be configured to support loads applied by the overshot assembly 100. In operation, it is contemplated that a recessed portion 78 and the wedge portion 82 can be sized and shaped to accommodate radial and axial movement of the latching members 114 as described herein.

The overshot assembly 100 can further comprise a distal spring 172 positioned within the central bore 108 of the distal body portion 104 in substantial alignment with the common longitudinal axis 102. In these aspects, the distal spring 172 can be positioned between and in engagement with a distal wall 174 of the distal body portion 30 and the distal portion 76 of the spindle 110. In addition or alternatively, and with reference to FIG. 3A, a proximal spring 173 can be positioned between the spindle 110 and the distal body portion 104 to bias the spindle proximately.

Optionally, in exemplary aspects, and as shown in FIGS. 2A and 2B, the wall 32 of the distal body portion 104 and the spindle 110 can define respective transverse bores 39, 79 that can be aligned when the latch assembly is in the deployed position to cooperatively define a through bore 81 (FIG. 6A). In these aspects, it is contemplated that when the latch assembly is in the deployed position, a locking pin 184 (FIG. 8 ) can be inserted through the aligned transverse bores 39, 79 of the distal body portion 30 and the spindle 110 to restrict axial movement of the distal body portion relative to the spindle and thereby retaining the latch assembly in the deployed position. It is further contemplated that the head assembly 300 can define its own transverse bores 304 (e.g., two transverse bores on opposing sides of the head assembly) that are positioned to align with the transverse bores of the distal body portion 104 and the spindle 110 when the latch assembly is positioned in engagement with the head assembly 300 (FIG. 6A) as further disclosed herein (e.g., when the latch assembly engages a groove within the head assembly). In use, it is contemplated that the locking pin 184 can pass through the aligned transverse bores of the distal body portion 104, the spindle 110, and the head assembly to lock the relative axial positions of these components. It is further contemplated that the locking pin can function as a safety feature during handling of the overshot and mated head assembly (including an inner tube) outside of the drilled hole. During manual or automated handling outside of the hole, the locking pin can be configured to prevent the accidental release of the head assembly in response to sufficient inertia, bumping, or impact.

Locking Sleeve

It is contemplated that the overshot assembly 100 can advantageously be coupled to the head assembly in order to lift the head assembly for positioning the head assembly in the drill string and removing the head assembly from the drill string. Accordingly, it can be desirable to retain the latching assembly in the deployed position in order to inhibit release from the head assembly. As further disclosed herein, a locking sleeve can be rotated to selectively retain the latching assembly in the deployed position.

Referring to FIGS. 1-2B, a sleeve 120 can be rotatably coupled to the distal body portion 104 about the longitudinal axis 102. The sleeve 120 can be configured to selectively lock the spindle 110 to retain the latching assembly 114 in the deployed position and release the spindle to allow the latching assembly to move between the deployed position and the retracted position. For example, referring also to FIGS. 3C and 3D, according to some aspects, the spindle 110 can comprise at least one projection 122 (e.g., optionally, three equally circumferentially spaced projections 122) that extends radially outwardly, through a slot 123 in the distal body portion 104 and is received within internal grooving 124 of the sleeve 120. In some aspects, the internal grooving 124 can comprise a circumferential groove 125 and, for each projection 122, a respective axially extending groove 128 that intersects the circumferential groove 125.

The circumferential groove 125 of the internal grooving 124 can define a stop surface 126 that engages each projection 122 to inhibit movement of the spindle 110 when the sleeve 120 is in a first rotational position (FIG. 3B). Rotation of the sleeve to a second rotational position (FIG. 3A) can position each projection 122 out of alignment with the stop surface 126 and in alignment with the respective axially extending grooves 128 that permit longitudinal travel of the projections 122 therein. Accordingly, when the sleeve 120 is in a first rotational position, the spindle 110 can be inhibited from longitudinal movement relative to the distal body portion 104. Thus, when the sleeve 120 is in the first rotational position, the latching assembly 112 can be retained in the deployed position. When the sleeve 120 is in the second rotational position, the spindle 110 can be permitted to move longitudinally relative to the distal body portion 104, thereby allowing the latching assembly 112 to be movable about and between the deployed position and the retracted position.

In some optional aspects, the spindle 110 can comprise a main body portion 111 and at least one set screw 130 threadedly coupled thereto, wherein the set screw(s) 130 defines the projection(s) 122.

In some aspects, one or more detent plunger assemblies 186 (or other detent structures) can extend from the sleeve 120 to engage the distal body portion 104. The detent plunger assemblies 186 can comprise a housing that is received within the sleeve 120, a ball, and a spring that biases the ball axially into the distal body portion 104. The distal body portion 104 can define recesses 188 that can align with the detent plunger assemblies to retain the sleeve in a fixed rotational position. For example, the distal body portion 104 can define recesses 188 a that receive the balls of the detent plunger assemblies when in the sleeve 120 is in the first rotational position and recesses 188 b that receive the balls of the detent plunger assemblies when the sleeve 120 is in the second rotational position. In some aspects, the overshot assembly 100 can comprise a plurality of detent plunger assemblies 186 (e.g., three equally circumferentially spaced detent plunger assemblies spaced 120 degrees apart). Optionally, some or all of the detent plunger assemblies can be removable to decrease the resistance to rotation of the sleeve.

As further stated herein, during head assembly retrieval, if the locking sleeve 120 is in the first rotational position, the latching assembly 112 can be inhibited from engaging the head assembly, requiring removal, adjustment of the locking sleeve 120, and re-deployment. Accordingly, to avoid such an inadvertent occurrence, the locking sleeve can comprise a blocking assembly 131 that is configured to inhibit insertion of the overshot assembly when the locking sleeve 120 is in the (locking) first rotational position.

According to some aspects, the sleeve 120 can have an inner surface 142 and an outer surface 144 and can define one or more radial openings 146 that extend between the inner surface and outer surface. The radial openings 146 can be configured to at least partially receive respective blocking elements. At least one blocking element 140 can be radially movable within the sleeved toward and away from the longitudinal axis 102. For example, the blocking elements 140 can be radially movable within the openings 146. The one or more blocking elements 140 can be pins, balls, rollers, cylinders, cam-shaped elements, and the like.

The sleeve 120 can have a radially outermost surface 148 that is defined by the portion of the outer surface 144 that is farthest from the longitudinal axis 102. When the sleeve 120 is in the first rotational position and retaining the latching assembly in the deployed position, the at least one blocking element can be held radially outward of the radially-outermost surface 148 of the sleeve.

The at least one blocking element can extend sufficiently from the longitudinal axis of the overshot assembly to inhibit insertion of the overshot assembly into a drill string. The distance from the longitudinal axis can be selected based on the dimensions of the drill string and overshot assembly. It is contemplated that the blocking elements can increase the operative diameter of the overshot assembly so that the operative diameter of the overshot assembly is greater than the inner diameter of the drill string. For example, the operative diameter can be greater the inner diameter of the drill string by at least 1/32 inch.

Referring also to FIG. 4 , the distal body portion 104 can have an outer surface 150 that engages the blocking elements 140 to bias the blocking elements radially outwardly. When the sleeve is in the first rotational position with respect to the distal body portion, the outer surface 150 of the distal body portion that engages the blocking elements 140 can be at a first radial distance from the longitudinal axis 102. When the sleeve is in the second rotational position with respect to the distal body portion, the outer surface 150 of the distal body portion that engages the blocking elements 140 can be at a second radial distance from the longitudinal axis 102 that is shorter than the first radial distance. For example, the distal body portion 104 can define flats 151 (or grooves or other radially recessed features) that are rotationally aligned with the blocking elements 140 when the sleeve 120 is in the second rotational position to enable the blocking elements to be recessed (radially inward) within the openings 146 relative to their respective radial positions when the sleeve 120 is in the first rotational position.

The outer surface 144 of the sleeve 120 can define, in cross sections in planes perpendicular to the longitudinal axis 102, respective outer traces. For example, the outer surface 144 of the sleeve 120 of the illustrated embodiment can have outer traces that are generally triangular with rounded corners and are consistent or generally consistent along the length of the sleeve. Likewise, the outer surface of the distal body portion 104 can have, in cross sections in planes perpendicular to the longitudinal axis 102, respective outer traces. It is contemplated that the outer surface 144 of the sleeve 120 can define a trace that is the same or substantially the same as an outer trace of a cross section of the distal body portion. Accordingly, when the sleeve 120 is in the second rotational position, the respective outer surfaces 144, 150 of the sleeve 120 and the distal body portion 104 can cooperate to define a generally continuous surface profile (See FIG. 12 ). When the sleeve 120 is in the first rotational position, the respective outer surfaces 144, 150 can be rotationally offset to provide a discontinuous surface profile (See FIG. 14 ). In this way, the sleeve 120 and distal body portion 104 can cooperatively provide a visual indication of whether the sleeve 120 is in the first rotational position or the second rotational position.

It is further contemplated that the overshot assembly can comprise an indicator that indicates when the overshot assembly is in the first rotational position. For example, as can be seen in FIGS. 1 and 7 , the distal body portion 104 can define a first marking 152 (e.g., an arrow), and the sleeve 120 can define a second marking 154 (e.g., an icon of a locked padlock). Rotational alignment of the first marking 152 and the second marking 154 can indicate that the sleeve is in the first rotational position. In exemplary aspects, when the sleeve 120 and distal body portion 104 have outer surfaces 144, 150 with generally triangular profiles having corner surfaces joining the three planar faces that define the generally triangular profiles, it is contemplated that the second marking 154 can be provided on one or more (optionally, each) of the corner surfaces. The sleeve can further define a third marking 156 (e.g., and icon of an unlocked padlock) that, when aligned with the first marking 152, can indicate that the sleeve 120 is in the second rotational position. In exemplary aspects, when the sleeve 120 and distal body portion 104 have outer surfaces 144, 150 with generally triangular profiles having corner surfaces joining the three planar faces that define the generally triangular profiles, it is contemplated that the third marking 156 can be provided on one or more (optionally, each) of the planar faces.

Bypass Flow Paths

Referring to FIGS. 1 and 5 , in some aspects, it is contemplated that the overshot assembly 100 can have a length and an outer surface 160 that extends along the length. At least a portion of the outer surface 144 of the sleeve 120 and the outer surface 150 of the distal body portion 104 can define respective portions of the outer surface 160 of the overshot assembly 100. The outer surface 160 of the overshot assembly 100 can comprise at least one surface 162 that cooperates with the inner surface 164 of the drill string 10 to define at least one bypass flow path 166 therebetween. For example, the outer surface 144 of the sleeve 120 and the outer surface 150 of the distal body portion 104 can define one or more respective planar surfaces 168, 170 (e.g., three respective planar surfaces) to collectively define the at least one inner surface 162 that cooperate with the inner surface 164 of the drill string to provide the bypass flow paths 166. In this way, the bypass flow paths 166 can increase the rate of tripping the overshot assembly, thereby improving both overshot deployment and head assembly retrieval efficiency. It is contemplated that the generally triangular cross section can maintain the overshot assembly in an axially centralized position within the drill string.

Referring also to FIGS. 15 and 16 , the overshot assembly 100 can omit the sleeve 120. The distal body portion 104 of the overshot assembly 100 can have a central axis 200 and a length along the central axis. The outer surface of the distal body portion can define, along at least a portion of the length, one or more (e.g., three) drill string engagement portions 202 (e.g., comprising or corresponding to respective engagement surfaces) positioned at a first radial distance from the central axis of the distal body portion. The one or more drill string engagement portions 202 can be configured to bias against and slide along the inner surface 164 of the drill string 10. Thus, it is contemplated that the first radial distance can be about the same as the radius of the distal body portion.

The distal body portion 104 of the overshot assembly 100 can further define one or more recessed portions 204 that are inwardly spaced from said first radial distance from the central axis. A plane 208 that is perpendicular to the central axis 200 of the distal body portion extends through each drill string engagement portion 202 of the at least one drill string engagement portion and each recessed portion 204 of the at least one recessed portion.

Accordingly, the one or more recessed portions 204 can cooperate with the inner surface 164 of the drill string 10 to define a respective bypass flow path 166 therebetween. Thus, the one or more recessed portions 202 can define the at least one surface 162 of the outer surface 160 of the overshot assembly 100 that cooperates with the inner surface 164 of the drill string 10 to define at least one bypass flow path 166 therebetween. It is contemplated that the flow paths 166 disclosed herein can greatly increase tripping rates. For example, during distal (toward the drill bit) tripping downhole (or otherwise moving away from the drill head or drill rig), tripping can often be through fluid within the borehole, and the flow of said fluid through said flow paths 166 can decrease fluid resistance to thereby increase tripping rate (e.g., under the weight of the overshot assembly). It is contemplated that proximal tripping (out of the borehole or otherwise towards the drill head or drill rig) can likewise be increased, as the load on the wireline can be reduced by reducing fluid resistance with the flow paths 166.

In some aspects, the drill string engagement portion(s) 202 can define a portion of a cylindrical surface. Optionally, the drill string engagement portion(s) 202 can comprise two or at least two drill string engagement portions 202. In further aspects, and as shown, the drill string engagement portion(s) 202 can comprise three engagement portions. In some optional aspects, the drill string engagement portions 202 can be equally circumferentially spaced around the distal body. For example, as shown, when three drill string engagement portions 202 are used, the drill string engagement portions can be spaced at 120 degree intervals about the central axis 200 of the distal body portion.

In some aspects, the recessed portions 204 of the outer surface of the distal body portion 104 can be defined by a planar or generally planar surface. In further aspects, the recessed portions 204 can be defined by radially outwardly concave surfaces or radially outwardly convex surfaces.

Optionally, at least a portion of each recessed portion 204 of the one or more recessed portions can be inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance. That is, in some aspects, at least a portion of each recessed portion 204 can be spaced radially outwardly from the central axis of the distal body portion 104 by 80% or less (for example, about 60% to about 75%) of the first radial distance (between the central axis and the at least one drill string engagement portion 202). In some exemplary aspects, the first radial distance can range from about 1.05 inches to about 1.20 inches or from about 1.40 inches to about 1.60 inches, and the recessed portions 204 can be spaced radially outwardly from the central axis by about 0.70 inches to about 0.90 inches or from about 0.90 inches to about 1.10 inches.

In some aspects, in the plane 208, the outer surface of the distal body portion can define a first area. The first area can be less than 95%, or less than 90%, or less than 85%, or less than 80%, or less than 75% of an area of a circle 210 in the plane 208 that circumscribes the drill string engagement portions 202. In exemplary aspects, the area of the circle 210 can range from about 4 square inches to about 7 square inches, and the area occupied by the distal body portion can be about 2.75 square inches to about 4.75 square inches. As can be understood, in the plane 208, the bypass flow paths 166 can collectively define an area that is equal to, or substantially equal to, the area of the circle that circumscribes the drill string engagement portions 202 less the first area.

Tunable Length and Weight

Referring to FIG. 20 , it is contemplated that the proximal body portion 106 can comprise a plurality of segments 270 that can be added or removed to adjust the length and, correspondingly, the weight of the overshot assembly 100. It is contemplated that the bypass flow paths 166 can increase tripping speed, and the weight of the overshot assembly 100 can be tuned to prevent excessive speed. Still further, it is contemplated that a shorter overshot assembly can be desirable, and the length can be selected accordingly. For example, it is contemplated that a dry hole can require a lower weight for pressing on the overshot release mechanism (e.g., pushing the spindle distally to release the head assembly).

Pivotal Movement of Distal Body Portion Relative to Proximal Body Portion

Referring to FIGS. 17 and 18 , in some aspects, a proximal portion 178 of the spindle 110 can be pivotally coupled to the proximal body portion 106, e.g., via a ball joint or other pivot joint 180.

In some aspects, the proximal body portion 106 can comprise a first portion 212 and a second portion 214 that is coupled to the first portion by a swivel joint 215 so that the first portion can swivel relative to the second portion about the longitudinal axis 102 of the overshot assembly 100. The second portion 214 can define a socket 216. The distal body portion 104 can couple to a pivot element 220. The pivot element 220 can be received within the socket 216 so that the pivot element can pivot relative to the second portion 214 of the proximal body portion 106. For example, in some aspects, the pivot element 220 can comprise a ball 222 (or other shape (e.g., a cylindrical shape) that is complementary to the socket 216 and configured to pivot within the socket) and a stem 224. Accordingly, the pivot element 220 and the socket 216 can cooperate to define the pivot joint 180 (optionally, a ball joint).

In some aspects, the socket 216 can define at least one slot 218 that is configured to receive the stem 224 to enable the pivot element 220 (and, thus, the distal body portion 104) to pivot at least 85 degrees, at least 90 degrees, greater than 90 degrees, or about 90 degrees relative to the proximal body portion 106. Optionally, the socket 216 can define at least two of said slots 218. For example, the socket 216 can define two slots 218 on opposing sides of the second portion 214. Accordingly, in some aspects, the socket 216 can enable about 180 or at least 180 degrees of pivotal movement of the pivot element 220 (and, thus, the distal body portion 104) relative to the proximal body portion. In this way, the pivot joint 180 in combination with the swivel joint 215 between the first and second portions 212, 214 of the proximal portion of the overshot assembly 100 can enable the distal body portion 104 to pivot relative to the proximal body portion 106 within a hemispherical (one-half sphere) range (e.g., a pivotal range having a solid angle of about 2 PI steradians or at least 2 PI steradians).

In some aspects, the swivel joint 215 can comprise a bearing 240 (e.g., a thrust bearing) that is captured between a bushing 242 and a lock nut 244. A swivel element 246 can extend through the bushing 242, through the bearing 240, and threadedly couple to the lock nut 244. In this way, the swivel element 246 can swivel relative to the bushing 242. The second portion 214 of the proximal body portion 106 can threadedly couple to the swivel element 246.

In some aspects, the pivot element 220 can define a recess 230 that receives a retainer element 232 (e.g., a ball) that is biased (e.g., via a spring 234) into the recess when the distal body portion 104 is oriented parallel to, or generally parallel to, the proximal body portion 106. In this way, during tripping, the distal and proximal body portions 104, 106 of the overshot assembly can be axially aligned (e.g., parallel or generally parallel) with each other.

Head Assembly Adapter

Referring to FIG. 19 , it is contemplated that the head assembly 300 can comprise an adapter 308 that is configured to couple to a corresponding overshot. The adapter 308 can be secured to the rest of the head assembly 300 (e.g., a main body 312 of the head assembly) via a fastener, such as, for example, a locking pin 310 (e.g., a spring pin). In exemplary aspects, the adapter 308 is received within a portion of the main body 312, and a locking pin 310 extends through aligned openings (through-bores) of the main body 312 and the adapter 308.

Methods of Use

In some aspects, the overshot assembly can be configured for manipulating the head assembly (e.g., positioning the head assembly in the drill string or removing the head assembly from the drill string). For example, it is contemplated that the overshot assembly can be coupled to a wireline for lifting the head assembly (after coupling between the overshot assembly and the head assembly as disclosed herein). In use, it is contemplated that the overshot assembly can permit positioning and/or removal of the head assembly with minimal physical interaction between the drill rig operators and the overshot assembly (and other components of the drill string and/or drill rig).

Referring to FIGS. 3A, 6A and 6B, the distal body portion 104 can be inserted into the end of the head assembly 300 until the latching assembly 112 engages the head assembly. For example, the distal body portion can define a shoulder 182 that can meet a proximal rim 302 of the head assembly. The head assembly can define an inner groove, lip, ridge, or the like, that is configured to receive the latching members 114 of the latching assembly 112 to inhibit removal of the distal body portion 104 without a threshold longitudinal pulling force between the head assembly and the distal body portion.

Referring to FIGS. 1, 7 and 8 , the locking sleeve 120 can be rotated from the second rotational position (FIG. 7 ) to the first rotational position (FIG. 8 ), thereby inhibiting the movement of the latching assembly to release the head assembly 300. The head assembly 300 can further define through holes 304 that can be aligned with the respective transverse bores 39, 79 (FIG. 2B) of the distal body portion and the spindle, and a locking pin 184 can be received through the aligned holes 304 and bores 39,79 to further inhibit release of the head assembly 300 from the overshot assembly 100.

Referring to FIGS. 1 and 9 , the overshot assembly can be used to lift the head assembly 300 into the drill string. Optionally, a release guard 400 can be inserted between the head assembly 300 and the overshot assembly. The release guard 400 can comprise a generally flat plate 402 (e.g., metal or durable polymer) that defines a slot 404 that can be received below the shoulder 182 of the distal portion 104 of the overshot assembly. The slot can have a width that is slightly larger than the end of the distal portion 104 that is distal of the shoulder 182. The release guard 400 can further define an opening 406 for receiving an operator's hand to pull the release guard out from between the head assembly and the overshot assembly.

Referring to FIGS. 10 and 11 , once the head assembly 300 is positioned in the drill string, the release sleeve can be rotated from the first rotational position to the second rotational position, and the locking pin 184 can be removed.

Referring to FIG. 11 , if the weight of the head assembly alone is not enough to cause the latching assembly 112 to release the head assembly from the overshot assembly, the overshot assembly can be lowered until the release guard 400 impacts the drill string, thereby creating an impact force that dislodges the head assembly from the overshot assembly.

Referring to FIG. 12 , with the sleeve 120 in the second rotational position, the overshot assembly 100 can be deployed within the drill string to retrieve the head assembly. Once engaged, the overshot assembly 100 can be retrieved via wireline. Referring to FIGS. 13 and 14 , once returned to the proximal end of the drill string, the sleeve 120 can be rotated to the first rotational position, and the locking pin 184 can be inserted through the aligned holes 304 and bores 39,79 (FIG. 2B). The overshot assembly 100 can then be used to lift and transport the head assembly from the drill string.

Referring also to FIG. 1 , to decouple the overshot assembly 100 from the head assembly 300, the sleeve 120 can be rotated to the second position. An operator can then move the proximal body portion 106 (and, thus, the spindle 110) distally relative to the distal body portion 104 to release the latching assembly 112 and decouple the head assembly 300 from the overshot assembly 100.

Exemplary Aspects

In view of the described products, systems, and methods and variations thereof, herein below are described certain more particularly described aspects of the invention. These particularly recited aspects should not however be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language literally used therein.

Aspect 1: An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion defining a central bore; a proximal body portion that is coupled to the distal body portion; a spindle disposed within the central bore of the distal body portion, wherein the spindle is slidable relative to the distal body portion along the longitudinal axis; a latching assembly operatively coupled to the distal body portion and configured for movement about and between a retracted position and a deployed position; a sleeve that is rotatably coupled to the distal body portion about the longitudinal axis; and at least one blocking element that is radially movable within the sleeve toward and away from the longitudinal axis, wherein, when the sleeve is in a first rotational position, the latching assembly is retained in the deployed position and the at least one blocking element is held radially outward to a first radial position, and wherein, when the sleeve is in a second rotational position, the latching assembly is movable between the retracted position and the deployed position and the at least one blocking element is permitted to move radially inwardly from the first radial position.

Aspect 2: The overshot assembly of aspect 1, wherein, when the sleeve is in the first rotational position, the spindle is inhibited from longitudinal movement relative to the distal body portion, and, wherein, when the sleeve is in the second rotational position, the spindle is permitted to move longitudinally relative to the distal body portion.

Aspect 3: The overshot assembly of aspect 2, wherein the spindle comprises a projection extending radially outwardly, wherein the sleeve defines internal grooving that cooperates with the projection of the spindle, so that when the sleeve is in the first rotational position, the spindle is inhibited from longitudinal movement relative to the distal body portion, and, wherein, when the sleeve is in the second rotational position, the spindle is permitted to move longitudinally relative to the distal body portion.

Aspect 4: The overshot assembly of aspect 3, wherein the spindle comprises a main body portion and a spring-biased detent coupled thereto, wherein the spring-biased detent defines the projection.

Aspect 5: The overshot assembly of any one of the preceding aspects, wherein, when the sleeve is in the first rotational position, the at least one blocking element extends sufficiently radially from the longitudinal axis of the overshot assembly to inhibit insertion of the overshot assembly into a drill string.

Aspect 6: The overshot assembly of any one of the preceding aspects, wherein the spindle defines at least one recessed portion that at least partially receives the at least one blocking element when the sleeve is in the second rotational position.

Aspect 7: The overshot assembly of any one of the preceding aspects, wherein the latching assembly comprises at least one latch member.

Aspect 8: The overshot assembly of aspect 7, wherein the wall of the distal body portion defines at least one distal radial opening extending from the outer surface of the wall to the central bore of the distal body portion, wherein the at least one distal radial opening is configured to at least partially receive the at least one latch member when the latching assembly is in the deployed position.

Aspect 9: The overshot assembly of any one of the preceding aspects, wherein at least a portion of the distal body portion has a cross section that defines an outer trace that is substantially the same as an outer trace of a cross section of the sleeve.

Aspect 10: The overshot assembly of any one of the preceding aspects, wherein the overshot assembly has a length along the longitudinal axis, wherein the overshot assembly defines at least one surface that is configured to cooperate with an inner surface of a drill string to define a flow path that extends across the entire length of the overshot assembly.

Aspect 11: The overshot assembly as in aspect 10, wherein the at least one surface comprises at least one planar surface.

Aspect 12: The overshot assembly as in any one of the preceding aspects, wherein the overshot assembly defines three planar surfaces that are parallel to the longitudinal axis of the overshot assembly and equally spaced about a circumference of the overshot assembly.

Aspect 13: The overshot assembly as in any one of the preceding aspects, further comprising an indicator that indicates when the sleeve is in the first rotational position.

Aspect 14: The overshot assembly of aspect 10, wherein the indicator comprises a first marking on the distal body portion and a second marking on the sleeve, wherein alignment between the first marking and the second marking corresponds to the sleeve being in the first rotational position.

Aspect 15: The overshot assembly as in any one of the preceding aspects, wherein the sleeve has an outer surface and an inner surface, wherein the sleeve defines at least one radial opening extending between the outer surface and the inner surface of the sleeve, wherein the at least one radial opening is configured to at least partially receive a respective blocking element of the at least one blocking element.

Aspect 16: The overshot assembly as in any one of the preceding aspects, wherein the distal portion of the spindle defines a first driving surface, wherein the latching assembly is positioned in engagement with the first driving surface when the latching assembly is in the deployed position, and wherein upon axial advancement of the distal body portion in a proximal direction relative to the longitudinal axis, the first driving surface is configured to permit movement of the latching assembly toward the retracted position.

Aspect 17: The overshot assembly as in any one of the preceding aspects, further comprising a distal spring positioned within the central bore of the distal body portion in substantial alignment with the longitudinal axis of the distal body portion, wherein the distal spring is positioned between and in engagement with the wall of the distal body portion and the spindle.

Aspect 18: The overshot assembly as in any one of the preceding aspects, wherein the at least one blocking element comprises at least one ball.

Aspect 19: The overshot assembly as in any one of the preceding aspects, wherein, when the sleeve is in the first rotational position, the at least one blocking element is held radially outward of a radially-outermost surface of the sleeve, wherein when the sleeve is in the second rotational position, the deployed position, and the at least one blocking element is not held radially outward of the radially-outermost surface of the sleeve.

Aspect 20: A method of using the overshot assembly as in any one of the preceding aspects, comprising: inserting the distal end of the overshot assembly into a proximal end of a head assembly; and rotating the sleeve until the sleeve is in the first rotational position.

Aspect 21: The method of aspect 20, further comprising: inserting at least a portion of the head assembly into a drill string; rotating the sleeve until the sleeve is in the second rotational position; and releasing the head assembly from the overshot assembly.

Aspect 22: The method of aspect 21, wherein releasing the head assembly from the overshot assembly comprises: inserting a release guard between the overshot assembly and the head assembly; and lowering the head assembly until the release guard impacts a proximal end of the drill string.

Aspect 23: A method of using the overshot assembly as in any one of aspects 1-19, comprising inserting the overshot assembly into a drill string when the sleeve is in the second rotational position.

Aspect 24: A system comprising: a drill string; a head assembly that is configured for insertion into the drill string; and an overshot assembly as in any one of aspects 1-19.

Aspect 25: An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion defining a central bore; a proximal body portion that is coupled to the distal body portion; a sleeve that is rotatably coupled to the distal body portion about the longitudinal axis; and at least one blocking element that is radially movable within the sleeve toward and away from the longitudinal axis, wherein, when the sleeve is in a first rotational position, the at least one blocking element is held radially outward of a radially-outermost surface of the sleeve, wherein, when the sleeve is in a second rotational position, the at least one blocking element is not held radially outward of the radially-outermost surface of the sleeve, and wherein, when the sleeve is in the first rotational position, the at least one blocking element extends sufficiently radially outward of the sleeve to inhibit insertion of the overshot assembly into a drill string.

Aspect 26: An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion defining a central bore; a proximal body portion that is coupled to the distal body portion; a sleeve that is rotatably coupled to the distal body portion about the longitudinal axis; and wherein, when the sleeve is in a first rotational position, the latching assembly is retained in the deployed position, and wherein, when the sleeve is in a second rotational position, the latching assembly is movable between the retracted position and the deployed position.

Aspect 27: An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string; at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion.

Aspect 28: The overshot assembly of aspect 27, wherein each drill string engagement portion of the at least one drill string engagement portion is a portion of a cylindrical surface.

Aspect 29: The overshot assembly of aspect 27 or aspect 28, wherein the at least one drill string engagement portion comprises at least two drill string engagement portions.

Aspect 30: The overshot assembly of any one of aspects 27-29, wherein the at least one drill string engagement portion comprises three drill string engagement portions.

Aspect 31: The overshot assembly of any one of aspects 27-30, wherein the drill string engagement portions are equally circumferentially spaced around an inner surface of the distal body portion.

Aspect 32: The overshot assembly of any one of aspects 27-31, wherein each recessed portion of the at least one recessed portion comprises a planar or generally planar surface.

Aspect 33: The overshot assembly of any one of aspects 27-32, wherein at least a portion of the at least one recessed portion is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance.

Aspect 34: The overshot assembly of any one of aspects 27-33, further comprising: a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises: a first portion; and a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.

Aspect 35: A system comprising: an overshot assembly as in any one of aspects 27-34, wherein the overshot assembly defines a through bore; a head assembly defining at least one hole that is axially aligned with the through bore of the overshot assembly; and a locking pin that extends through the through bore of the overshot assembly and the at least one hole of the head assembly to axially retain the head assembly relative to the overshot assembly.

Aspect 36: A system comprising: an overshot assembly as in any one of aspects 27-34; and a head assembly comprising: a main body; an adapter that is configured to receive a portion of the overshot assembly, wherein the adapter is at least partly received within the main body; and a fastener that secures the adapter to the main body.

Aspect 37: An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion.

Aspect 38: The overshot assembly of aspect 37, wherein each drill string engagement portion of the at least one drill string engagement portion is a portion of a cylindrical surface.

Aspect 39: The overshot assembly of aspect 37 or aspect 38, wherein the at least one drill string engagement portion comprises at least two drill string engagement portions.

Aspect 40: The overshot assembly of any one of aspects 37-39, wherein the at least one drill string engagement portion comprises three drill string engagement portions.

Aspect 41: The overshot assembly of any one of aspects 37-40, wherein the drill string engagement portions are equally circumferentially spaced around an inner surface of the distal body portion.

Aspect 42: The overshot assembly of any one of aspects 37-41, wherein each recessed portion of the at least one recessed portion comprises a planar or generally planar surface.

Aspect 43: The overshot assembly of any one of aspects 37-42, wherein at least a portion of the at least one recessed portion is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance.

Aspect 44: The overshot assembly of any one of aspects 37-43, further comprising: a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises: a first portion; and a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.

Aspect 45: A system comprising: an overshot assembly as in any one of aspects 37-44, wherein the overshot assembly defines a through bore; a head assembly defining at least one hole that is axially aligned with the through bore of the overshot assembly; and a locking pin that extends through the through bore of the overshot assembly and the at least one hole of the head assembly to axially retain the head assembly relative to the overshot assembly.

Aspect 46: A system comprising: an overshot assembly as in any one of aspects 37-44; a head assembly comprising: a main body; an adapter that is configured to receive a portion of the overshot assembly, wherein the adapter is at least partly received within the main body; and a fastener that secures the adapter to the main body.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, certain changes and modifications may be practiced within the scope of the appended claims. 

1. An overshot assembly having a longitudinal axis, the overshot assembly comprising: a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion.
 2. The overshot assembly of claim 1, wherein each drill string engagement portion of the at least one drill string engagement portion is a portion of a cylindrical surface.
 3. The overshot assembly of claim 1, wherein the at least one drill string engagement portion comprises at least two drill string engagement portions.
 4. The overshot assembly of claim 1, wherein the at least one drill string engagement portion comprises three drill string engagement portions.
 5. The overshot assembly of claim 1, wherein the drill string engagement portions are equally circumferentially spaced around an inner surface of the distal body portion.
 6. The overshot assembly of claim 1, wherein each recessed portion of the at least one recessed portion comprises a planar or generally planar surface.
 7. The overshot assembly of claim 1, wherein at least a portion of the at least one recessed portion is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance.
 8. The overshot assembly of claim 1, further comprising: a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises: a first portion; and a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.
 9. A system comprising: an overshot assembly having a longitudinal axis and comprising: a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion, and wherein the overshot assembly defines a through bore; a head assembly defining at least one hole that is axially aligned with the through bore of the overshot assembly; and a locking pin that extends through the through bore of the overshot assembly and the at least one hole of the head assembly to axially retain the head assembly relative to the overshot assembly.
 10. A system comprising: an overshot assembly having a longitudinal axis and comprising: a distal body portion having a central axis, a length along the central axis, and an outer surface, wherein the outer surface of the distal body portion defines, along at least a portion of the length: at least one drill string engagement portion positioned a first radial distance from the central axis of the distal body portion, wherein the at least one drill string engagement portion is configured to bias against and slide along an inner surface of a drill string, at least one recessed portion that is radially inwardly spaced from said first radial distance from the central axis, wherein said at least one recessed portion is configured to cooperate with the inner surface of the drill string to define a respective flow path along the length of the distal body portion, wherein a plane that is perpendicular to the central axis of the distal body portion extends through each drill string engagement portion of the at least one drill string engagement portion and each recessed portion of the at least one recessed portion; and a head assembly comprising: a main body; an adapter that is configured to receive a portion of the overshot assembly, wherein the adapter is at least partly received within the main body; and a fastener that secures the adapter to the main body.
 11. The system of claim 9, wherein each drill string engagement portion of the at least one drill string engagement portion of the overshot assembly is a portion of a cylindrical surface.
 12. The system of claim 9, wherein the at least one drill string engagement portion of the overshot assembly comprises at least two drill string engagement portions.
 13. The system of claim 9, wherein the at least one drill string engagement portion of the overshot assembly comprises three drill string engagement portions.
 14. The system of claim 9, wherein the drill string engagement portions of the overshot assembly are equally circumferentially spaced around an inner surface of the distal body portion.
 15. The system of claim 9, wherein each recessed portion of the at least one recessed portion of the overshot assembly comprises a planar or generally planar surface.
 16. The system of claim 9, wherein at least a portion of the at least one recessed portion of the overshot assembly is inwardly spaced from said first radial distance from the central axis by at least 20% of said first radial distance.
 17. The system of claim 9, wherein the overshot assembly further comprises: a proximal body portion that is coupled to the distal body portion, wherein the proximal body portion comprises: a first portion; and a second portion that is coupled to the first portion by a swivel joint so that the first portion can swivel relative to the second portion about the longitudinal axis of the overshot assembly, wherein the second portion defines a socket, wherein the distal body portion comprises a pivot element that is received within the socket so that the pivot element is pivotable about an axis that is transverse to the longitudinal axis of the overshot assembly by at least 85 degrees.
 18. The system of claim 10, wherein each drill string engagement portion of the at least one drill string engagement portion of the overshot assembly is a portion of a cylindrical surface.
 19. The system of claim 10, wherein the drill string engagement portions of the overshot assembly are equally circumferentially spaced around an inner surface of the distal body portion.
 20. The system of claim 10, wherein each recessed portion of the at least one recessed portion of the overshot assembly comprises a planar or generally planar surface. 